1. Field of the Invention
The present invention relates to an information recording apparatus for recording information in a magnetic recording section provided on a photographic film, an information reading apparatus for reading that information, and an information recording and reading method for recording information in the magnetic recording section and reading the information recorded.
2. Description of the Related Art
A technique has been proposed in which a photographic film, particularly a negative film, is coated with a transparent magnetic material, a magnetic recording section is formed along the traveling direction of the negative film, and information concerning the negative film and information concerning images printed on the negative film are recorded in the magnetic recording section (e.g. International Publication Number WO 90/04205). According to this technique, since information concerning images can be recorded in the magnetic recording section at positions physically corresponding to respective image frames in which the images have been recorded, the time and trouble involved in retrieval of information can be reduced. For instance, the date and time of photographing, a place of photographing, photographing conditions, and so on can be recorded at the time of photographing with the camera. In addition, at a laboratory (hereinafter referred to as the lab), corrected values of exposure conditions can be recorded in the magnetic recording section after checking the image frames with a notcher/puncher or the like, and the exposure conditions and the like of the respective image frames determined by taking into consideration the aforementioned photographing conditions and corrected values during printing onto a photographic paper using a printer can be recorded in the magnetic recording section. For this reason, at the time of a reordering, print processing can be effected under the same conditions if the exposure conditions and the like thus recorded are read.
When information magnetically recorded on a magnetic recording medium is read, there are cases where reading failures occur, including the loss of information (bit omission) due to the nonuniformity in the traveling speed of the magnetic recording medium, defects in the medium, dust, or the like, and a change in the content of information (transformation of bits) due to the inclusion of noise from an external source. To solve this problem, in such fields as digital audio, wireless communication, and computers, the following attempts are made to reduce the occurrence of reading failures such as those described above: That is, an attempt is made to control the nonuniformity in recording medium travel during the recording and reading of information to a fixed level or below by means of a PLL, clock detection or the like. At the time of recording information, verification is effected in which the information once recorded is read and a comparison is made between the same and the information persisting prior to the recording, or an error detection/correction typified by parity check is adopted.
Meanwhile, in the field of photographic processing, the recording and reading of information with respect to the magnetic recording section of a photographic film are handled by apparatuses whose photographic film transporting systems are provided with different configurations. For instance, the information is recorded by a camera and the information is read by a printer. As a result, the possibility of occurrence of the aforementioned reading failures is high. In the field of photographic processing, there has been no prior art in which the above-described error detection and correction technique is applied to the information recorded in the magnetic recording section of a photographic film. Therefore, in the event that a reading failure has occurred and resulted in the loss of information or a change in its content, problems are encountered by the reading apparatus, which is operated on the basis of the information which has been read. In addition, in the event that a synchronization error occurs due to the fact that the clock cannot be detected during reading or for another similar reason, there occurs a so-called burst error in which consecutive bits of information recorded in the magnetic recording section are lost or transformed in large volumes, in which case the detrimental effect is particularly large.
In addition, particularly in a camera, the variation of the film advancing speed occurs frequently as it is affected by, among other things, fluctuations in the voltage of a battery serving as a power source for a film-transporting motor, and fluctuations in the torque for withdrawing the photographic film from a cartridge. Furthermore, cameras are used by general users and could be placed under various environments unsuitable for information recording, e.g., a high- or low-temperature environment, a high-humidity environment, and an environment in which the cameras are subjected to vibrations or dust enters the same. For this reason, even if information is simply recorded in the magnetic recording section of the photographic film, reading failures can possibly occur or the contents of the information may change due to the variations in the film advancing speed during information recording or the effect of the surrounding environment. Hence, the reliability of the recording information is low.
To prevent a decline in the reliability of recording information due to the variation of the advancing speed, it is conceivable to provide the camera with a device which has a read head for reading the information recorded in the magnetic recording section and which is adapted to effect the aforementioned verification. Such an arrangement, however, causes the camera to become large in size and heavy in weight. Since the camera is premised on an assumption that it is carried by the user, it is undesirable that the camera becomes large in size and heavy in weight. Thus, it has been difficult for the camera to be provided with the device for improving the reliability of recording information.